Newsletter no. 17 – Monday 27 September, 2021

This is the web-based version of Stretch Therapy Newsletter no. 17

What you should know about hip flexors and back pain

By Kit Laughlin

If you search the internet, you’ll find that many experts report that tight hamstrings are the cause of low back pain, but in my experience, tight hamstrings are an effect of another cause. Let me explain.

The most common posture seen in the Western world today is an “APT” (as the clinicians like to say); this term is shorthand for “Anterior Pelvic Tilt”. In other words, this term describes a physical shape where the pelvis is tilted forward from “normal*” (we will reconsider this term below) and the main effect of this change in position is that the lumbar “lordosis” (the concave curve in the lower part of the back) is exaggerated, and this change in shape is always accompanied by increased tension in the lumbar muscles (quadratus lumborum and erector spinae, the large muscles on either side of the lumbar spine).
hip flexors 1

The main reason for an APT is that we spend most of our working and recreational lives sitting these days. It's a simple thing to demonstrate experimentally, but the seated position for most people is also close to the position of maximum shortness for the hip flexors themselves. When I say “hip flexors”, I'm using this as a shorthand for three muscles: psoas, iliacus, and rectus femoris. The last-mentioned muscle is the main culprit in someone who doesn't do any stretching routinely – that is to say, rectus femoris, which crosses both the hip joint and the knee joint, will be chronically tight, and it will be, functionally, the tightest of the three hip flexors. These three muscles, when shorter than desirable, always tilt the pelvis forward and increase the curve in the lumbar spine.

Another quick test: lie down on the floor, trying to relax as much as you can. Now slide a hand in under your lumbar spine from the side – can you fit your hand between your back and the floor? If you are loose enough in the hip flexors, your lumbar spine will rest on the floor. This is extremely rare (based on our experience of classes and workshops, where this test is always done, usually just before we work on hip flexors!), and this is the reason most people need something under the back of their knees to feel comfortable lying on the floor. Lifting the back of the knees away from the floor with a bolster, for example, slackens rectus femoris, and that allows the pelvis to roll back a little and then the lower back can rest on the floor).

If we turn this image on its side and look at the one on the left, we see the most common shape people’s bodies make these days:

hip flexors 2

In today's culture most people experience their life as stressful, and particularly in the last 12 months (Covid-19). The experience of stress, while quite well understood from a chemical perspective (the “fight or flight response”), also has the effect of increasing the tension of all the muscles in the body – and the ones which are already short or tight from other causes can signal pain once their capacity to absorb stress is reached. And because people spend so much time in the sitting position, with the consequence of shortened hip flexors, the brain experiences this pattern as the ‘normal*’ (in other words, this must be ’normal', because that is how we are spending the bulk of daily life!) – and the pattern is reinforced.

Pain in the hip flexors themselves is unusual, but back pain, partly the result of the anteriorly tilted pelvis, is extremely common. In almost all instances of low back pain, the hip flexors play a partial, or full, causal role. Clinically, we have noticed that increasing the length of the hip flexors immediately decreases the tension held in the lumbar spine muscles themselves in most of the people we have worked with. We have palpated back muscles on many workshops pre- and post-hip flexor stretching, and this effect is real and significant. In other words, the tension experienced in the lower back muscles is a necessary adaptation to the anterior pelvic tilt. When the spine is straighter, less effort is required to maintain posture in the upright, load-bearing position, and all involved muscles relax.

An APT is itself a sufficient** cause of tight hamstrings – but the main reasons for tight hamstrings are two. The first is that we spend our life sitting, and we sit on our bottom and our hamstrings, with the necessary reduction in blood flow that this entails. The second is that because most people don't take these long muscles through anything like a fraction of their potential range of movement, they simply adapt to the movement patterns they are subjected to. As well, through a phenomena known as reciprocal inhibition reflex, if your hip flexors are tight, then your glutes are going to be inhibited – this is just a fancy way of saying that the glutes will tend to be lazy, or inactive, or simply not very strong. Strong, active glutes are absolutely necessary for any kind of efficient movement patterns.

All this can be changed: if the hip flexors are loosened in the non-back pain suffering person, the experience immediately is a lightening of the experience of being in one’s body, and walking is immediately felt as being ‘easier’ or ‘freer’. We hear this on workshops literally every time we run them. And for the back-pain sufferer, loosening the hip flexors can feel like the weight of the world has been removed from your shoulders, and the pain you were feeling has reduced, or even gone completely. If back pain (or neck pain) is a problem for you, you must loosen your hip flexors and see what happens – if the hip flexors are involved in your problem, the change in the tension in your back and neck will be noticed immediately.

One tight hip flexor, or both hip flexors tight (and I will explain what I mean by ‘tight’ below) are sufficient** causes of low back pain directly, and middle back and neck pain, less directly. Sufficient, as used here, means that alone, tight hip flexors can cause back pain. There are many other muscular factors, too, of course, but if the hip flexors are  tight, back pain may be in your future.

relaxed lunge

[Click here to view a video tutorial of the above solo hip flexor stretch.]

See how my thigh is in the same line as my spine, and with my lumbar spine completely straight? We regard this as the minimum hip flexor available length, simply to be able to move around freely in daily life. And the reason is, if your hip flexors do not have this length, as soon as you stand up and take your weight on your feet, your lumbar spine will be curved backwards (the ‘lumbar lordosis’, as it’s called). This is because these same muscles attach to both the front of the lumbar spine and the front of the pelvis, and if not long enough, pull the pelvis and the lumbar spine forwards of the flatter position shown above (the right-hand image). Postural accommodation always occurs in the ‘least effort’ direction (by this, I mean whichever direction requires the least amount of energy to achieve, and maintain), and it is much easier for the lumbar spine to extend than the hip flexors lengthen.And having run workshops around the world for more than fifteen years, I can say with certainty that most attendees do not have this suppleness available. And how do we know that this kind of length is needed, or useful? Because literally hundreds of attendees have mentioned to us that as soon as they stretch their hip flexors properly (in other words, in a way that changes their free length–tension relationship), they notice that their feet rest more evenly on the floor; that any back tension (or pain) they had when they walked in with had gone, and the same for the middle back and neck pain I mentioned above. They all tell us they walk around ‘lighter’ or more freely.So, if there’s any doubt, you need to stretch your hip flexors! If you search on “hip flexors” here on the site, you will find what you need.

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* Normal is a statistical assessment – the term describes where the bulk of a standardly distributed population is found. Mathematically, this is about 68%. Assuming a symmetrical distribution, this part of the distribution is described as “one standard deviation from the mean”. 96% includes the second standard deviation as well as the first. Here’s an image taken from the net:


Any analysis of the movement capacities of the normal population will show you that very few people have much capacity to extend at the hip joint at all – and these movements are controlled completely by the hip flexors. In other words, with respect to both movement and freedom from back pain, we do not want to be normal in the statistical sense; we want to be exceptional (or ‘abnormal’!) in the range of movement sense. Many other human qualities benefit from this approach.** sufficient: this usage is from the world of philosophy (and medicine); it denotes a cause that, by itself, can create the problem being considered. There may be a number of sufficient causes for any problem. Sufficient in these frameworks is contrasted with “necessary”, the latter cause always being present in the problem under consideration.

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An aside: I did not have a ‘message’ that I was trying to push or sell when I started the classes that eventually became the ST system. Instead, I wanted to know what would happen if we loosened the restricted parts of the body, and together with the teachers over 30 years, we paid attention to what was happening in the classes; we talked about what we’d seen; and the insights gained in working with tens of thousands of people was collected – the Overcome Neck & Back Pain, and Stretching & Flexibility books, and the Stretch Therapy method came out of this process, and this continues today.


The Back Pain Relief Wiki

Here you will find the latest and most-relevant information on the real causes of back pain, and how to treat them yourself.


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The Overcome Back Pain Course (video)

As the name suggests, this is our latest offering on how to use exercises to treat your own back pain. For convenience, these are six follow-along sessions – load and hit 'play'!


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Overcome Neck & Back Pain (book)

First published 1995, now in its 4th edition, this book has had three complete rewrites, each incorporating feedback and suggestions from both students and patients. This is the best self-help manual available – it comprises stretching, relaxation, and strengthening exercises.


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A note from a student

Wall Quad Hip Flexor If You Do Only One Stretch Today, This Is The One
[Click here to view a video tutorial of the wall quad–hip flexor stretch.]

This is incredible. I’m 27 years old and struggling immensely with recurring lower back pain as well as painfully tight hips, hamstrings and quads. I’ve tried lots of different things to try and help these problems, but I just followed along with this stretch for the first time and it’s made the world of difference. It was very uncomfortable at first, and it took me 3–4 attempts to get through the whole video, but having now followed it through the change is magnificent. Thank you so much Kit!

Jawwaad H., a comment left on the ST YouTube channel